RCS "$Id: Equiv.sig,v 1.5 1998/08/13 11:34:59 pxs Exp $";
signature EQUIV =
sig
   structure PG : POLYGRAPH

(* Is there an admissible bisimulation between graphs' initial states? *)
   val equiv : ('_a * '_a -> bool)
(* admissible: can the states be admitted in same block of a bisim? *)
     -> ('_a PG.state ref * '_a PG.state ref list) *
     ('_a PG.state ref * '_a PG.state ref list)
     (* graph type returned from TG fns *)
     -> bool

end

